Humans are extracting excessive moisture from the Earth, disrupting the planet's global water cycle. (See photo)

Scientists have been emphasizing for years the climate crisis looming over our planet, reiterating that human activities significantly impact all of the Earth's systems. In a new study spanning nearly 20 years of observations, researchers have found that the global water cycle is changing in unprecedented ways, according to PHYS.org.

According to co-author of the study, NASA Goddard Space Flight Center researcher Sujay Kumar, he and his colleagues determined that human intervention in the planet's global water cycle is actually more significant than previously believed. Most of the shifts noted by the researchers are driven by activities such as agriculture, and they believe these changes could affect ecosystems and water resource management, particularly in specific regions.

These shifts described by the researchers have implications for people worldwide. The lead author of the study, NASA Goddard Space Flight Center researcher Wanshu Ni, stated that it was previously assumed that the water cycle fluctuated only within a certain range, but now scientists believe these shifts have consequences for people around the globe. At least, this assertion holds true for some specific regions.

The authors of the study hope that their findings will serve as a roadmap for improving how scientists assess the variability of water resources and influence how the global community plans for sustainable resource management, especially in areas where changes are particularly noticeable.

One striking example of human impact on the water cycle is Northern China, which suffers from persistent drought. At the same time, vegetation in certain regions continues to thrive, partly because producers are still irrigating the land. By extracting more and more water from the Earth's depths, such interconnected human interventions often lead to complex effects on other variables of the water cycle, such as evapotranspiration and runoff.

In the new work, Ni and colleagues focused on three different types of shifts in the cycle:

• reduction of water in groundwater reservoirs;
• shifts in seasonality;
• changes in extreme events, such as 100-year floods occurring more frequently.

The team utilized data collected via remote sensing from 2003 to 2020 from several NASA satellite sources. They also used products from the Moderate Resolution Imaging Spectroradiometer satellite instrument to provide information on vegetation health. As a result, the researchers were able to model continental water flows and reserves across the planet.

The study's results indicate that Earth system models used for predicting the future global water cycle must evolve to integrate the current effects of human activity.